An optical system for determining an object's position is known of the type comprising
a laser frequency generator, PA0 an emission convergent optical system installed at the generator output to direct the generator frequency towards the object along at least one axis, PA0 a photoelectronic receiver sensitive to laser radiation, PA0 a receiver optical system to direct some of the laser frequency that the object diffuses towards the receiver, PA0 and a processing circuit connected to the receiver's electric output. PA0 the generator is equipped with a laser transmitter with controllable beam frequency, PA0 the system also is equipped to modulate the laser transmitter's frequency as a function of time according to a predetermined law; this emission optical system is chromatic and is capable of focusing the laser's radiation in a concentrated area on the axis; the said law is predetermined to ensure displacement versus time of the concentrated area along the said axis in the direction of the object; the surface of the object transmits to the reception optical system a luminous signal once the concentrated radiation beam area encounters the surface; the receiver delivers an electric signal once it picks up the luminous signal, PA0 the processing circuit is connected to the modulation equipment to shift the laser emitter frequency; it comprises a timer for measuring the time interval between the beginning of the frequency shift and the moment when the receiver delivers the electric signal; this time interval reflects the position of the said concentrated area when the object's surface intercepts this area.
This type of system is described in the French patent application published 24th Dec. 1982 under number 2508160. In such a system, the receiver is installed along an average reception axis intersecting the axis of the emission optical system near the object whose position is to be determined. The receiver comprises at least two photoelectric measuring detectors which deliver electric signals when the object approaches the system. The system also consists of a photoelectric control detector positioned towards the object. The processing circuit is fitted with a logic circuit capable of selecting one of the signals delivered by the measurement detectors to take the necessary measurement. The processing circuit also comprises a divider circuit designed to determine the ratio between the amplitude of the electric signal delivered by the measurement detector described and the amplitude of the electric signal delivered by the control detector. Finally, it incorporates a computing circuit able to determine the distance separating the object from the system from the measured ratio.
The system outlined above have two disadvantages.
It is relatively complex. Furthermore, it is difficult to use it for determining several points of the object and therefore for detecting the form and surface of the object.
The present invention aims to overcome these disadvantages.